For many years, rows of cotton were spaced at least 38 to 40 inches apart. Recently, however, farmers have noted a substantial increase in productivity when row width is narrowed; i.e., spacing between cotton rows being about 30 inches. Besides an increase in cotton productivity, narrow row widths allow for uniformity between seed planting operations. For these and other reasons, there is an incentive to plant cotton in narrow rows.
Conventional self-propelled cotton harvesters utilize individual harvesting units mounted at a forward end of the harvester. Cotton harvesters having up to four individual harvesting units arranged in side-by-side relationship relative to each other have been designed to increase cotton picker production.
Each harvesting unit typically includes two picker rotors comprised of numerous circularly driven picker bars. Each picker bar mounts a plurality of rotatably driven, radially extending picker spindles for removing the cotton from the plant. A pair of doffer assemblies together with a picker spindle moistening assembly are typically provided in combination with each harvesting unit. Each doffer assembly, having numerous doffer pads, is provided to remove the cotton from the individual picker spindles. The picker spindle moistening assembly includes a series of vertically arranged moistening pads for adding moistening fluid to each of the cotton picker spindles before they are introduced to the cotton plant.
Typically, the harvesting units are connected to a support structure which extends laterally across a forward end of the cotton harvester. To adjust for row width, the harvesting units are moved laterally across the support structure. Although considerable design effort has resulted in cotton harvester units of reduced size and weight, the usage and required operation of such units mandate a relatively large size mechanism having considerable weight. Because of their size and weight, however, laterally moving the units to adjust row width is difficult and usually requires considerable efforts on the part of the operator. As a result, lateral adjustment of the harvesting units is inconvenient, difficult, and is usually avoided whenever possible.
The harvesting capacity of the cotton harvester varies as a function of the number of harvesting units associated therewith. As will be appreciated, a support structure for accommodating four side-by-side harvesting units which are arranged to harvest adjacent rows of cotton planted 40 inches apart must be substantially wider than the support structure used to accommodate two harvesting units arranged to harvest adjacent rows of cotton narrowly spaced approximately 30 inches apart.
Providing a single support structure for accommodating all the numerous combinations of row spacings and harvesting capacities is impractical because the distance between the ends of such support structure would be too wide for conveniently transporting the cotton harvester. In view of today's economics, a farmer wanting two or three narrow row capacity does not want the added cost, weight and inconvenience of a support structure which is wider than that which he requires.
Having separate one-piece support structures for adapting the cotton harvester to each of the required widths results in increased manufacturing costs, area distribution costs, and inhibits a farmer from subsequently increasing the capacity of his machine unless he buys a wider support structure. Moreover, wider support structures present problems in that they are difficult to ship from one location to another and are inconvenient to handle.
Another problem with cotton harvesters relates to inspection and servicing of the harvesting units. Although desirable, it is not practical to laterally move the harvesting units relative to each other along the support structure to provide added clearance for inspection and servicing of the harvesting units. As an example, to remove an inboard harvesting unit for servicing usually requires removal of the adjacent outboard harvesting unit. Simultaneous removal of both harvesting units causes problems due to the bulkiness and weight of the separate harvesting units. As will be appreciated, a support structure which is longer than required only adds to the burdensome problem of removing the harvesting units therefrom. Moreover, removal of the outboard harvesting unit before the removal of the inboard harvesting unit takes additional time, a premium during harvest season.
U.S. Pat. No. 4,803,830 to S. A. Junge et al. discloses a support arrangement for cotton harvester row units. The support arrangement includes a row unit support frame which is connected by a four-bar linkage structure to a main frame of the cotton harvester. The support frame includes longitudinally spaced, horizontal and laterally extending beams or rails which are interconnected by a cross beam. Notably, one rail is arranged immediately adjacent the center of gravity of the row units.
Each of the individual row units is suspended on the rails by a roller assembly including laterally spaced rollers which may include bearings to improve performance. The rollers maintain point contact with a surface forming a part of or connected to the laterally extending rails so that the row units can be moved laterally to effect the desired spacing between adjacent row units by rolling the row units on the surfaces defined by the lateral rails. Once the harvesting units are properly spaced, they are locked into position by pins.
The rail and roller structure disclosed in the Junge et al. patent contributes to easier movement of the row units and thereby enhances access to the row units for servicing and general maintenance. The substantial weight of each row unit, however, is localized at the point of contact established between each roller and the rail which supports that roller. It has been found that, over time, such point contact causes pitting of the surface over which the roller rides. As will be appreciated, pitting of the rail surface will inhibit smooth, lateral movement of the roller thereover and can cause difficulty in aligning the pins to lock the row units in position. It has also been found that the substantial weight of the row unit causes the rollers to lockup and/or reduce the life of the bearings. Roller lockup and/or bearing failure will only add to the farmer's frustration in effecting servicing of the harvesting units.
During a cotton harvesting operation, there is a significant amount of dirt, dust and trash entrapped in the environmental air surrounding the harvester. Some of such dirt, dust and trash settles on the rail and furthermore causes wear on the rollers and bushings or bearings normally provided therefore. As will be appreciated, roller wear or bearing failure will frustrate and interfere with smooth lateral movement of the harvesting units.
Although the above-described support structure enhances row spacing, the provision of a rail which laterally extends above and across the top of each row unit inhibits complete access to the row units. As is evident, the location of the extended rail above the center of gravity of the harvesting unit permits only limited access to the row units and daily service and inspection operations can not be made easily and conveniently. Moreover, the location of the rail above the center of the harvesting units hinders or interferes with operator visibility of the row units from the cab region of the harvester.